With advances in technology, medical devices are capable of significantly improving the treatment and/or management of various diseases or illnesses. One such medical device is an insulin delivery system capable of delivering insulin to a diabetic individual and managing the delivery of insulin. One example of an insulin delivery system includes an insulin delivery device or infusion pump that is secured to the user to deliver the insulin and a wireless, hand-held device that communicates with the delivery device to control and manage insulin delivery. The hand-held device may program the infusion pump with personalized insulin delivery instructions and monitor the operation of the infusion pump, thereby facilitating the management of diabetes. The insulin infusion pump may deliver insulin according to a delivery program that provides different doses of insulin at different times of day, for example, a basal program that provides different basal rates over different time segments. The insulin infusion pump may also deliver bolus doses of insulin, for example, to correct for high blood glucose or in connection with an event, such as a meal, that is likely to affect blood glucose. Extended bolus doses may be delivered, for example, over an extended period of time to avoid a high initial dose of insulin and to allow extended insulin action.
Existing insulin delivery systems may calculate appropriate amounts of insulin to be delivered based on a number of factors. Insulin delivery systems may calculate an appropriate bolus dose based on, for example, a blood glucose level and an expected carbohydrate intake. Another factor that may be considered when determining an appropriate bolus dose is insulin on board (IOB). Because insulin takes time to be processed in the body, residual insulin often remains in the body for a period of time after receiving the insulin and keeps working after the carbohydrates have been processed. To avoid delivering a bolus dose that would result in too much insulin (e.g., insulin stacking), the IOB may be subtracted from a bolus dose that would otherwise be appropriate (e.g., for a given blood glucose level and carbohydrate intake). Because insulin is delivered over an extended period of time during an extended bolus, factoring in the IOB during such extended boluses is more difficult.